ksplice-create(8) Create a set of kernel modules for a rebootless kernel update


ksplice-create [OPTIONS] --patch=PATCH_FILE KERNEL_SOURCE

ksplice-create [OPTIONS] --diffext=EXTENSION KERNEL_SOURCE

ksplice-create [OPTIONS] --git=COMMIT KERNEL_SOURCE

ksplice-create [OPTIONS] --prebuild KERNEL_SOURCE


ksplice-create creates a set of Ksplice kernel modules that, when loaded, will apply a user-specified source code patch to the running binary kernel.

Before you use ksplice-create on a patch, you should confirm that the desired source code change does not make any semantic changes to kernel data structures---that is, changes that would require existing instances of kernel data structures to be transformed (e.g., a patch that adds a field to a global data structure would require the existing data structures to change). If you use Ksplice on a patch that changes data structure semantics, Ksplice will not detect the problem and you could experience kernel problems as a result.

The to-be-applied source code patch can be specified by providing a patch(1) file (--patch=PATCH_FILE) or by providing a file extension (--diffext=EXTENSION).

If a file extension is specified, then the desired source code patch will be determined by comparing all of the files in the KERNEL_SOURCE directory tree whose names end with the extra extension EXTENSION against the corresponding files without the extra extension. Only the new files containing the extra extension in their filenames should be modified.

Here is an example of using a file extension to specify a patch:

 $ cp KERNEL_SOURCE/kernel/sys.c KERNEL_SOURCE/kernel/sys.c.prctl_fixed
 [edit sys.c.prctl_fixed to include the desired changes]
 $ ksplice-create --diffext=.prctl_fixed KERNEL_SOURCE

KERNEL_SOURCE must be a directory containing the to-be-updated kernel's original source code. If your Linux distribution applies patches to the Linux kernel during the kernel build process, then those patches must be applied to the KERNEL_SOURCE directory before invoking ksplice-create on that directory. ksplice-create will not modify the source code in the KERNEL_SOURCE directory tree, but it will perform a kernel build in that directory tree.

ORIG_CONFIG can be used to specify the directory containing the to-be-updated kernel's original .config file and original System.map file (the files should have exactly those names). ORIG_CONFIG defaults to KERNEL_SOURCE/ksplice.

The default gcc(1) compiler and as(1) assembler on the system should be as close to the compiler and assembler originally used to build the running kernel as possible. If the current compiler and linker are too different from the original compiler and linker, ksplice-apply will abort when applying the update.

ksplice-create outputs a tar(1) file, compressed with gzip(1), containing the desired Ksplice update modules. This tarball will be created in the current directory, and it can be manipulated using the other Ksplice utilities, such as ksplice-apply.

The first time that ksplice-create is invoked on a KERNEL_SOURCE directory, it must build that kernel from scratch, which is much slower than the rest of the update-creation process. --prebuild can be used to perform this initial kernel build without providing a source code patch.

In order to patch a function that has previously been patched by Ksplice, the user needs to ensure that the KERNEL_SOURCE directory provided to Ksplice contains the source for the currently running kernel, including any patches that have previously been applied by Ksplice.


Builds a Ksplice update out of the given patch(1) file PATCH_FILE.
Builds a Ksplice update using the modified source files with names ending in EXTENSION. The patch will be determined by comparing all of the files in the KERNEL_SOURCE directory tree whose names end with the extra extension EXTENSION against the corresponding files without the extra extension.
Builds a Ksplice update using the commit COMMIT in the Git working tree KERNEL_SOURCE. The original state corresponding to the running kernel is remembered in the Git ref refs/ksplice/pre, which will be created from the current HEAD if it does not yet exist (and can be changed using the --series option). Therefore, the source code change to be applied corresponds to the output of git diff ksplice/pre COMMIT.
Compiles the original source code that will be needed to build future Ksplice updates. If any Ksplice updates have previously been built in the KERNEL_SOURCE tree, the source files in the tree are reverted to their original state.
Specifies that the current state of the KERNEL_SOURCE tree should be used as the original source that corresponds to the running kernel. If a Ksplice update has recently been built in the KERNEL_SOURCE tree, this option specifies that the Ksplice update being built should be applied after the previous update in series. This option can be used with --prebuild to forget the previous original state and perform no other action.
For a patch that includes changes to kernel modules, in addition to building a hot update that can be applied to the running kernel, this option will cause ksplice-create to generate a set of new modules based on the updated source code. These modules can be used to replace the kernel modules stored on disk, where they can later be loaded normally after part of the hot update has been applied using ksplice-apply(1) --partial.
-v, --verbose
Causes ksplice-create to print debugging messages about its progress. Using multiple -v options increases the verbosity. The maximum is 2.
-j JOBS, --jobs=JOBS
Specifies the number of jobs to run simultaneously while performing kernel builds. ksplice-create also honors the environment variable CONCURRENCY_LEVEL.
Can be used to pass options to patch(1). If this option is NOT specified, then -p1 is passed to patch. If this option is specified, then only the specified options will be passed to patch. This option can be repeated in order to pass multiple options to patch. This option is ignored when the to-be-applied source code patch is specified using --diffext.
Specifies the unique value that will be used as the identifier of the Ksplice update. This identifier will, for example, appear in the name of the update tarball. By default, a random 8-character ID will be generated.


Please report bugs to <[email protected]>.


Jeff Arnold, Anders Kaseorg, and Tim Abbott


Copyright (C) 2007-2009 Ksplice, Inc.

This is free software and documentation. You can redistribute and/or modify it under the terms of the GNU General Public License, version 2.